Tuning mechanism



Sept 15 194% B. A. SCHWARZ ETAL 2,296,061 g TUNING MECHANISM AFiled web.l 15, 1940 2 sheets-sheet 1 Sweaters 1 f' (Ittomegs Sept 15 1942@ E. A. SCHWARZ ET m.. 2,296061 TUNING MECHANI SM Filed Feb. l5, 3.940l 2 SheetsSheet 2 Smoentors l um i S. Gttornegs Patented y Sept. l5, 1942 TUNING MEcnANrsM Bertram A. Schwarz and Ludwig Fichter, Kokomo, Ind., assignors to General Motors Corporation, petroit, Mich., a corporation o! Delaware Application February 15, 1940, Serial No. 319,044

(Ci. 'i4- 10) Claims.

This invention relates to indexing mechanism and more specifically to indexing mechanism utilized with tuning means for automatically tuning a radio receiver to certain predetermined stations.

Since most receivers are utilized mainly toreceive transmitted signals from a relatively small number of stations which are usually those within the vicinity in which the receiver is located, it has become very popular to provide on each radio receiver a series of means whereby the tuning t mechanism may be set to receive signals from any one of a plurality of stations by merely moving the button a short distance. The motion may be obtained either by pushing the member longitudinally or rotating it to a certain degree. Some of the earlier mechanisms applied to obtain this result were very cumbersome and included a greatV and claims and the illustrations of the accoml panying drawings, in which:

Figure 1 is a front elevation of a set embodying our invention;

Figure 2 is a transverse sectional view ytaken on line 2-2 of Figure 3; e

Figure 3 is a top plan view of the tuning mechanism of our invention;

Figure 4 is an enlarged detail view showing a portion of the apparatus for operating the indicator;

Figure 5 is a transverse sectional view line 5--5 of Figure 3;

Figure 6 is a top plan' View of the cover plate carrying the indicating mechanism which is applied over the tuning mechanism;

Figure 7 is an elevational view of the mechanism alone, taken on line I--l of Figure 6 and showing the supporting plate in section;

Figure 8 is an enlarged detail view of the connections between the tuning mechanism and rotatable member;

Figure 9 is an enlarged detail view showing the taken on cooperation between the movable force applying v means and the movable shaft, taken online 9-9 of Figure 10;

Figure 10 is an enlarged transverse sectional view showing one of the automatic tuningl devices; and

Figure 11 is a detail view of one of the adjustable means which may be moved to change the automatic setting.

Referring now more specifically to the drawings, .the front panel 2 of`a set is shown in Figure l. This panel is provided of course with an opening such as 4 throughwhich a dial 6 yis visible and over said dial an indicating needle 8 may be moved to provide information as to the station to which the radio receiver is tuned. Also extending through the iront panel 2 are two comparatively large knobs IU and I2, I0 being the manual tuning knob and I2 `the switch and Vautomatic volume control which is conventional as in any of the present sets. Between these two lmobs I 0 and I2 there are provided a series of smaller buttons I4 which in the present instance are iive in number but may be of any number, dependent upon how many stations .the manufacturer and/or user decides will be the convenient number. These buttons are the automatic tuning buttons and above each is provided a small opening I6 in which may be secured indicia showing by call letters which station that particular button is set for.

The tuning of a radio receiver `may be accomplished by varying either the capacity in the resonant circuits therein or the inductance so that varying values of either one will provide a resonance of the circuit over a desired band. In the particular instance shown, we have illustrated the tuning of aset by varying the inductance, but the present mechanism may as satisfactorily be connected to variable capacities without deviating from our invention in any way. Since the particular tuning mechanism per se forms no part of the present invention, it is shown in dotted lines as is the outside casing and in Figure 2 we iind an induction coil IB which is supported in the rear of the outer casing and within the center of which there is adapted to be moved a small core 20. Since there are several tunable circuits in a receiver in the various stages, it is necessary to provide a plurality of these for tuning the whole receiver and there are shown in dotted lines in Figure 3 three of .these variable inductances.

Within the forward portion of the casing there is provided a supporting bcx frame indicated generally at 22, having `the forward and rear pory tions bent upwardly to provide vertical front and rear walls 24 and 26. Within the forward wall there are provided a' series of openings 26 through which .the shafts of a series of rods 30 are carried for longitudinal movement. In alignment with these openings and in the rear wall there are provided a like series of openings 32 which support and trunnion the opposite ends of the rods 30. Applied to the forward end of the rod and rigidly secured thereon by gluing or other suitable means are the buttons I4 which extend'through the forward face of the casing. Press-fitted upon each rod 30 and directly inside the upper vertical wall 24 is a small washer'34 which acts as a stop to prevent the rod from being ejected forwardly inasmuch as it is spring-biased toward that position by a helical spring 36 which surrounds the inner end of the rod between the inner face of the rear wall 26 and a second washer 38 thereon.

Between thetwo washers 34 and 38 the rod 38 is threaded as at 48 and has mounted thereon an angled bracket 42, `as. best shown in Figure l1, said bracket being provided with a horizontal portion and two vertical portions 44 and 46 hav' ing therein threaded openings 48, the vertical portion 44 having an extending tip 58 which projects downwardly into a longitudinal slot 52 in the base of the member 22. Y This prevents the bracket from rotating with the rod 38 and pro- All of the rods 36 are exactly identical and the position of the adjustable member 42 along the threaded portion of each of the rods determines the indexing position of the tuning mechanism such as I8. The two end plates 66 and 62 of the box frame trunnion the ends of a transverse shaft 18 which extends the full width of the tuner and carries thereon at opposite ends two links 12, the links being connected to said shaft 18 adjacent one endY and having rigidly secured thereto at an intermediate point a second parallel longitudinal shaft 14 which is adapted to cooperate with any of the adjustable vides a screw feed for it along the axis. There is also provided on the forward face of the portion 44 a bulbous projection 54 whose purpose will be later explained. A small spring 56 which is slightly bowed is adapted to be inserted through the opening 45, between the upper portion of the member 42 and the threads of the rod to cause tension between the two so that there will be some force necessary to thread the member along the rod and the same will remain in a given Aset position. The tip of the rod which projects through the opening 32 in the vertical rear face 26 terminates in a small knob 58 which has a radial face adjacent the end of the rod.

There are also provided across the ends of the box frame 22 two end plates 66 and 62 and trunnioned therein is a flat plate 64 which is pivoted about one edge thereof. There is also provided a pair of springs 66, one end of each being connected adjacent the free end of this plate 64, the other end being connected to the frame so that the spring bias will force the plate upward to contact the knobs 58 on each of the longitudinal movable rods 36. The travel of these rods 36 is so designed that when they are in their innermost position the knob 58 will just pass over the inner edge of the spring-biased plate 64 as shown in the dotted line position in Figure 2, whereby the plate will act as a spring lock and prevent the rod from returning to its original outward position normally caused by the spring 36. The upper surface of this plate 64 is angular, as best shown in a section of Figure 2, and the outer surface of the knob 58 is tapered to substantially correspond to the slant of this surface so that as one rod is forced inwardly the plate is forced down to first release any other knob which may be locked in, before it itself passes the edge of the plate and is locked therein whereby only one rod at a time is locked in its innerward indexing position. 'I'here is also provided a resilient washer 68 around the end of the rod projecting through the rear frame member 26 so that as the spring 36 forces the rod 30 outwardly the head of the member 58 will rest against this resilient washer and prevent noise in operation.

members 42 for indexing purposes.V Connected to the upper end of the'links 12 is a third parallel shaft 16 to which are connected, through mechanism to be described, the tuning elements 20.

Adjacent the ends of the shaft 10 as shown in the lower portion of Figure 3 is a spring member `18, the body of which is wound around the shaft 10, one end extending out and being secured to the side frame member as shown in Figure 4 at 80, the other end extending up and being hooked over a projecting end of the upper shaft 16 as shown at 82. This spring-biasing means biases the assembly in a counterclockwise direction, as shown in Figure 2, which, it will be seen, is the position in which the tuning cores 28 will be substantially withdrawn from the central portion of the inductances I8.

The bulbous portion 54 of each adjustable bracket 42 is adapted to contact the forward surface of the shaft 14, as best shown in Figure 9, if the longitudinal rod is forced inward. This will cause the lever arms 12 to be rotated about their pivot on shaft 1D and therefore to carry' .plurality of portions of smaller diameter, such as shown at 84, and secured in each one of these.

depressed portions is one end of a connecting link 86, shown in detail in Figure 8, and having a forward hooked portion 88 which extends over the body of the .shaft 16. The opposite end of the connecting'link 86 has a small pin 92 therethrough to which is secured a bushing support 94 having therein an internally threaded bushing 96 within which the threaded shaft 98, which is an integral part of the tuning core 20, is threaded. 'I'his allows the position of the core to be adjusted. Secured around the pin 92 and the shaft 16 are two ends of a small tension spring |00 which spring maintains the shaft 16 in the inward circular portion in the opening in the hooked end 88. 'I'hus as the shaft 16 is rotated about the axis of the shaft 1,0, the mechanism just described connecting the shaft 16 with the member 20 causes the latter to move in and out of the induction coil I8. There are of course as many of these connecting mechanisms as there are tuning mechanisms which it is adapted to operate, and, as before mentioned, in the present instance there are three, as best shown in the dotted lines in Figure 3.

The manua1 tuning knob lo is connected to similar shaft 30' which is substantially identical to any one of the shafts formerly described, its detail being best shown by reference to Fixture 5 wherein it will be seen that the shaft Il' carries an additional collar Il! adapted to act as a stop on the inward motion 'of the shaft Il' as well as having a washer 34' to act as a stop. The traveling threaded angle 42' isfidentical to thetraveling angles 42 as is the spring bias I6' adapted to cause it to be biased against too loose y movementalong the threads. There is also a wardly until the mechanism locks over the plate and then is rotated to cause the angled bracket to travel back and forth, rotating the lever arms 12 about the pivot 1II until the desired station is received. The actuation thereafter of any of the automaticy knobs will cause the manual knob to be ejected.`

Covering the box frame is a top plate IUS which is adapted to be secured thereto by suitable screws or bolts and carrying thereon any desired lighting means such as a bulb |08 and also indicating lever mechanism such as III) which transmits the movement of the lever arms 12 to the indicating needle 8. This particular indicating mechanism provides straight line movement for the needle 8 by certain lever construction which however forms no part of the present invention. The operating mechanism for said indicating means comprises a lever I I2 pivotallyl mounted at II4 to one of the levers 12, as shown in `Figure 4 and at the lower portion of Figure 3, said lever Ii 2 also being connected to the upper end of the member 12 by a pin and slot connection IIB so that its position may be adjusted.` A pin II8 extends outwardly from the uppermost end of the lever II2 and has connected thereto a link |20, shown in dotted lines in Figure 4, to which is connected a suitable cord arrangement for transmitting the energy to the lever system above mentioned.

It will thus be evident that as the levers 12 are rotated about the shaft as a pivot, the tuning cores will be moved in and out of the associated inductance to cause necessary tuning of the radio receiver and at the same time the cord will transmit the necessary motion to the indicating needle 8 to show the position of the tuning mechanism, and, ordinarily, .with none of the buttons I4 or III pushed inwardly, the levers 12 are spring-biased to an outward or counterclockwise position.

In order to set up a plurality of stations on the automatic means associated with each of the buttons I4, it is only necessary to have the receiver in operation, then to depress one of the buttons I4 so that it locks the head of the member 58 over the edge of the plate, then r'otate the rod 30 so that the angled bracket 42 may move along the axis of the same until a predetennined station has been reached. 'I'he next button is then depressed to the same extent which of course causes the release of the first rod in a manner formerly described and then this rod is rotated until another station has been brought into proper adjustment. This is repeated for all of the ilve or more buttons provided.

3 If at any time it a desired to manually tune the set the button III is depressed and the oper-A ation is exactly the same as in any one of the automatic adjustments. A further advantage of this construction is that the manual tuning knob I0 may be used as an automatic station selector inasmuch as it will always return the set to the last station set up thereon. its action being exactly identical with the remaining buttons. I4.

It is also of course obvious that this same mechanism may be readily used to cause a variable condenser to rotate instead of actuating means for causing a core to be inserted within a coil to change the inductance as it would be very simple to connect to the shaft 1li means to rotate a variable condenser and therefore the present illustrations are only illustrative of\ the broader conception of our invention.

We claim:

l. In indexing mechanism for tuning means, means rotatable about a pivot connected thereto, a plurality of reciprocable and rotatable rods at least a portion of each being threaded, threaded adjustable means mounted on each and adapted to engage the rotatable means at a portion of its travel, means for locking the rods at the innermost position of travel at which position the adjustable means contactsthe rotatable means whereby rotation of the rodl will move the adjustable means and alter the position of the rotatable means and the associated tuning mechanism.

2. In indexing mechanism for tuning means, -an assembly of parallel shafts pivoted to rotate about the axis of one of them, means interconnecting the tuning means with a second of the shafts and a series of reciprocable means adapted to contact a third shaft to cause rotation of the assembly, said individual recprocable means alternatively actuating the third shaft.

3. In an indexing mechanism, a frame, a pivoted assembly mounted on the frame which it is desired to index, a plurality of rods mounted in the frame roughly at right angles to the assembly, said rods being capable oi' reciprocation, spring means to bias them in one direction, a second spring means to bias the assembly in one direction, threaded means over a portion of each rod, threaded brackets mounted thereon and having a projection to engage the frame to pre'- vent their rotation about the axis of the rods whereby as -the rods are rotated the brackets may be adjusted axially thereof, said brackets being adapted to contact the assembly and move it about its pivot against the spring-biasing pressure and locking means to maintain the Vreciprocating means at one extremity of its travel.

4. In an indexing device, a frame, means pivoted in the frame which it is desiredvto index to different angular positions, a rod rotatably and reciprocably trunnioned in the frame, spring means biasing the rod in one direction, a threaded portion on the rod, a bracket threaded thereon and having a projecting portion engaging a slot in the frame to prevent its rotation about the axis of the rod but permit it to travel therec along for adjustment and spring-biasing means to maintain the pivoted means against the bracket whereby the position of the pivoted means may be varied either by rotation or reciprocation of the rod and means for locking said rod at one extremity of travel.

5. In an indexing mechanism, a frame, a pivoted assembly carried thereby which it is desired to index to diiferent angular positions, a plurality of rods mounted in the frame at substantially right angles to the assembly for both rotation and reciprocation. stops to limit the reciprocal travel of the rods, spring-biasing means for each rod to cause it to remain normally at one extremity of travel, a threaded portion on each rod, a threaded bracket mounted on each threaded portion having a projecting portion, said frame having a plurality of slots therein in which the projecting portions travel, the brackets adapted to contact the assembly alternately, a pivoted plate carried by the rear of the frame vbelow the rods and spring-biased upwardly, knobs mounted on the inner ends of the rods adapted to slide over the plate and lock the rod so forced, the' action of the next operated rod releasing the one locked so that there can only be one rod locked in at one time, whereby when a rod is locked in the bracket thereon forces the assembly to a given position and the rod may be rotated to alter the position for slight adjustment and when the next rod having a diilerent setting is depressed the first rod will be released. Y

BERTRAM A. SCHWARZ. LUDWIG FIGHTER. v 

